NASA's Mars rover, Opportunity, is examining rocks at the edge of Endeavour Crater for signs that they may have been either transported by a flood or eroded in place by wind. The features were seen just outside the crater rim's crest above "Perseverance Valley," which is carved into the inner slope of the rim.<br/><br/>Researchers plan to drive Opportunity down Perseverance Valley after completing a walkabout survey of the area above it. The team is also considering possible explanations for how the slope might have changed. <br/><br/>The Opportunity mission has been investigating sites on and near the western rim of Endeavour Crater since 2011. The crater is about 22 kilometres across. <br/>